Polycrystalline diamond constructions with protective element

Abstract

PCD constructions as disclosed comprise a ultra-hard body attached with a metallic substrate along a substrate extending between the body and the substrate. The construction includes a protective feature or element that is configured to protect a metal rich region or zone existing in the construction from unwanted effects of corrosion or erosion. The protective element extends from the body over the interface and along a portion of the substrate and may be integral with the.

What is claimed is: 
     
       1. A cutting element construction comprising:
 a polycrystalline diamond body comprising a matrix of bonded together diamond crystals and a plurality of interstitial regions dispersed within the matrix, wherein the body has a top surface and a side wall surface extending axially downwardly from the top surface, wherein the side wall surface is cylindrical having a substantially constant diameter; 
 a metallic substrate attached to the polycrystalline diamond body along an interface extending between the polycrystalline diamond body and the substrate, wherein the substrate includes a reduced diameter section having a diameter that is less than a diameter of the body side wall surface and that projects outwardly into a recessed section of the body, and wherein the substrate includes a remaining diameter section that extends radially outwardly from a wall surface of the reduced diameter section to an outside wall surface of the substrate; and 
 a protective element comprising a band that extends circumferentially within at least part of an annular space between the substrate reduced diameter section wall surface and along the substrate remaining diameter section, wherein the band extends axially along the body side wall surface to the substrate remaining diameter section and extends beyond a region of the interface existing between a top surface of the substrate reduced diameter section and the body, wherein the band is integral with the polycrystalline diamond body, and wherein the band has a diamond volume content that is different from a diamond volume content in the body. 
 
     
     
       2. The cutting element construction as recited in  claim 1  wherein the protective element has an outside diameter that is substantially equal to both an outside diameter of the polycrystalline diamond body side wall surface and an outside diameter of the substrate. 
     
     
       3. The cutting element construction as recited in  claim 1  wherein the protective element has an angle of departure relative to the interface between the top surface of the substrate reduced diameter section and the body of 90degrees or more. 
     
     
       4. The cutting element construction as recited in  claim 1  wherein the protective element has a radial thickness that is substantially constant along the axial length of the protective element. 
     
     
       5. The cutting element construction as recited in  claim 1  wherein the protective element has a radial thickness that changes along the axial length of the protective element. 
     
     
       6. The cutting element construction as recited in  claim 1  wherein the protective element diamond volume content is greater than the diamond volume content in the polycrystalline diamond body. 
     
     
       7. The cutting element construction as recited in  claim 1  wherein the protective element extends an axial length of from about 50 to 500 micrometers. 
     
     
       8. The cutting element construction as recited in  claim 1  wherein the protective element extends circumferentially around the entire annular space of the substrate. 
     
     
       9. The cutting element construction as recited in  claim 1  comprising more than one protective elements that are spaced apart from one another circumferentially. 
     
     
       10. The cutting element construction as recited in  claim 1  wherein the protective element has a radial thickness of at least 25 micrometers. 
     
     
       11. A drill bit comprising a bit body and a number of the cutting element constructions as recited in  claim 1  connected thereto. 
     
     
       12. A drill bit comprising:
 a bit body having a number of cutting elements operatively attached thereto, the cutting elements comprising:
 a polycrystalline diamond body comprising a matrix of bonded together diamond crystals with a plurality of interstitial regions dispersed within the matrix, the body having a top surface and a cylindrical wall structure extending axially away from the top surface; 
 a metallic substrate joined together with the polycrystalline diamond body along an interface, wherein the body includes an inwardly recessed section and the substrate includes an outwardly projecting reduced diameter section that is disposed within the body inwardly recessed section, the substrate having a generally cylindrical outside wall surface; and 
 a protective element extending circumferentially around a wall section of the substrate reduced diameter section to an outside diameter of the substrate and extending axially from the polycrystalline diamond body wall structure, wherein the protective element extends axially over a region of the interface between the body recessed section and the substrate reduced diameter section that is rich in metal-solvent catalyst material wherein the protective element is formed from polycrystalline diamond and has a radial thickness of at least 25 micrometers, and wherein the protective element has an outside diameter that is the same as the polycrystalline diamond body. 
 
 
     
     
       13. The drill bit as recited in  claim 12  wherein the protective element is in the form of an annular band and has a radial thickness that is constant. 
     
     
       14. The drill bit as recited in  claim 12  wherein the protective element has an axial length of from about 75 to 250 micrometers as measured from an interface of the protective element with the substrate. 
     
     
       15. The drill bit as recited in  claim 12  wherein the protective element has a diamond volume content greater than the diamond volume content in another region of the polycrystalline diamond body. 
     
     
       16. A method for making a diamond bonded construction comprising:
 placing a volume of diamond grains adjacent to an interface surface of a metallic substrate, wherein the metallic substrate comprises a reduced diameter section extending axially outwardly a distance from a remaining section of the substrate, wherein the volume of diamond grains and the metallic substrate form an assembly; and 
 subjecting the assembly to a high pressure/high temperature process condition to sinter the diamond volume in the presence of a solvent metal catalyst to form a polycrystalline diamond body, to attach the polycrystalline body to the substrate, wherein a protective element of polycrystalline diamond is formed during the step of subjecting that extends axially from the body and fills an annular space between a wall surface of the substrate reduced diameter section and an outside diameter of the substrate, wherein the protective element has a diamond volume content that is different than a diamond volume content in another region of the polycrystalline diamond body. 
 
     
     
       17. The method as recited in  claim 16  wherein during the step of subjecting, the polycrystalline diamond body and protective element are integrally combined. 
     
     
       18. The method as recited in  claim 16  wherein before the step of placing, configuring the substrate to have the reduced diameter section, wherein the reduced diameter section has a constant diameter. 
     
     
       19. The method as recited in  claim 16  wherein during the step of subjecting, the protective element has a radial thickness of at least about 25 micrometers, and wherein the protective element has an outside diameter that is the same as the outside diameter of the polycrystalline diamond body. 
     
     
       20. The method as recited in  claim 16  wherein the protective element has an axial length of from about 50 to 500 micrometers as measured from an interface of the protective element with the remaining section of the substrate.